Ultram (Tramadol) has been widely available in Europe for years before its approval in the U.S., and despite being a powerful analgesic, it has fallen short of its claims to be virtually abuse-free.
Unlike Hydrocodone and Oxycodone, which are full opioid agonists, Tramadol works on in similar manner but in a combination of ways. The fact that it binds to opioid receptors in the brain is what gives it its ability to stave off withdrawal in some folk. However, because it may bind to these receptors without providing the FULL opiod agonist effect, it may actually induce withdrawal if there is sufficiently high levels of an existing agonist in the system.
While it may give a lesser, or at least different, "high", the fact that it occupies these recepters can still throw the system akimbo when it discovers that they are no longer bound. The extent to which it affects individuals varies, but due to the wonders of genetics and individuality, and although it has the potential to affect virtually everyone, the extent to which varies greatly.
If you do have an physical dependence or addiction that extends beyond your need for the medication, you may want to explore Subutex (buprenorphine), for which more information is available at the SAMHSA web site.